Fibrils of thermoplastic polymeric material may be prepared by flash spinning processes wherein an organic solvent solution, dispersion, emulsion or suspension of polymeric material in a fluid medium is extruded through an orifice under conditions of temperature and pressure wherein the liquid medium is rapidly vaporized or evaporated resulting in formation of polymeric fibrils. See, e.g., U.S. Pat. No. 4,211,737 wherein an organic solvent solution, dispersion or emulsion of fiber-forming polymeric material is extruded through a convergent-divergent DeLaval type nozzle.
Alternatively, U.S. Pat. No. 4,219,512 discloses a polymeric fibril making process wherein an organic solvent solution of polymeric material is introduced into a fluid precipitation medium under the action of mechanically generated shearing forces.
In accordance with the present invention, thermoplastic fibrils may be readily and conveniently made from an aqueous suspension of powdered thermoplastic polymeric material and especially an aqueous suspension of powdered polytetrafluoroethylene (PTFE).